Luo Han Guo (Iuohanguo) refers to the fruit of Siraitia grosvenori, formerly called Momordica grosvenori, a member of the Curcubitaceae. The plant is cultivated for its fruit Luo Han Guo, whose extract is nearly 300 times sweeter than sugar and has been used in China as a natural low-calorie sweetener and in traditional Chinese medicine to treat diabetes and obesity. Luo Han Guo is popularly considered a longevity aid and is used to balance heat buildup caused by internal conditions, life-forces, or external heat. It is used as an expectorant and antitussive to treat lung congestion, cough, other respiratory ailments, and sore throat. It also is used for constipation and chronic enteritis. Luo Han Guo is a low-caloric, low-glycemic food used as a natural sweetener in beverages and food.
Luo Han Guo is collected as a round green fruit that turns brown upon drying. The sweet taste of Luo Han Guo comes primarily from mogrosides, a group of terpene glycosides, present at the level of about 1% of the fleshy part of the fruit. Both the fresh and dried fruits are extracted to yield a powder that is 80% or more mogrosides. The mogrosides have been numbered, 1-5, and the main component is called mogroside-5, previously known as esgoside. Other, similar compounds from Luo Han Guo have been labeled siamenoside and neomogroside. The mixed mogrosides are estimated to be about 300 times as sweet as sugar by weight, so that the 80% extracts are nearly 250 times sweeter than sugar; pure mogrosides 4 and 5 may be 400 times as sweet as sugar by weight.
A process for making a useful sweetener from Luo Han Guo was patented in 1995 by Procter and Gamble Company in U.S. Pat. No. 5,411,755. As described in the patent application, the fruit itself, though sweet, has too many additional flavors that would make it unsuitable for widespread use as a sweetener, so P&G developed a method for processing it to eliminate the undesired flavors. In the P&G process, the fresh fruit is picked before ripening and allowed to complete its ripening during storage so that processing begins with the just-ripe fruit. The peel and seeds are then removed, and the mashed fruit becomes the basis of a concentrated fruit juice or puree that can be used in food manufacturing. Further processing involves using solvents to remove volatile and off-flavor components. Numerous sugar substitutes derived from Luo Han Guo by similar processes that isolate the sweet compounds are now readily available for manufacturing and for kitchen use.
Recent work on Luo Han Guo includes investigation of the antioxidant activity of the mogrosides (Shi H, et al., Antioxidant property of fructus momordicae extract, 1996 Biochemistry and Molecular Biology International 1996; 40 (6): 1111-1121.) and their potential use as cancer prevention compounds (Konoshima T and Takasaki M, Cancer-chemopreventive effects of natural sweeteners and related compounds, Pure Applied Chemistry 2002; 74(7): 1309-1316.). This suggested effect is based on the understanding that antioxidants can produce significant reversal or suppression of the early stage of cancer development, which has been an area of particular interest for tea drinking (Katiyar SK and Mukhtar H, Tea antioxidants in cancer chemoprevention, Journal of Cellular Biochemistry, Supplement 1997; 27: 59-67.). Further, Luo Han Guo and its sweetening component are often mentioned in relation to diabetes and obesity, because it can substitute for caloric sugars normally consumed in the diet.
Due to these neutral properties the potential application for natural sweetener composition is diverse, so this high quality sweetener can be used to replace sucrose in virtually every single food. Although sucrose, provides the most desirable taste to consumers, it is caloric and unhealthy. Furthermore, the natural sweetener composition is process friendly with virtually the same sweetening power as traditional sugar. But to be able to claim that you are using “natural sweetener” instead of sucrose provides a consumer friendly image and a positive sales argument. The carbohydrate fructose found in the natural sweetener composition is generally recognised as diabetic sweeteners, as compared to sucrose they are sugar substitutes and metabolised independent of insulin.
It has been also known numerous natural sweeteners are non-caloric; however, they exhibit sweet tastes that have different temporal profiles, maximal responses, flavor profiles, mouthfeels, and/or adaptation behaviors than that of sugar. Because of these differences, in a food or beverage, causes an unbalanced temporal profile and/or flavor profile. In addition to the difference in temporal profile, natural sweeteners generally exhibit:                (i) lower maximal response than sugar,        (ii) tastes including bitter, metallic, cooling, astringent, licorice-like taste, etc.,        (iii) sweetness which diminishes on iterative tasting.        
It is well known to those skilled in the art of food/beverage/pharmaceutical composition that the sweetener in a composition requires balancing of the flavor and other taste components. If the taste profile of natural sweeteners could be modified to impart specific desired taste characteristics to be more sugar-like, the type and variety of compositions that may be prepared with that sweetener would be expanded significantly. Accordingly, it would be desirable to selectively modify the taste characteristics of natural sweeteners.
Another important point for the food/beverage/pharmaceutical composition is processability. The natural sweetening composition must be easily handled, mixed with excipients even having a larger particle size and must be processed into beverage, food, pharmaceutical, oral, dietetic, veterinary or tobacco products without the known and expected problems such as segregation or de-mix during the process steps. It is usually related with the choice of the sweeteners and their amounts or ratios between them.
In this invention it is surprisingly found that, a specific amount of Luo Han Guo changes the taste balance of a food or beverage or pharmaceutical compositions. They are slower in onset and longer in duration than the sweet taste produced by sucrose.